---
title: "Fly.io"
sidebarTitle: "Fly.io"
description: "Integrate your app with Subtrace on Fly.io"
icon: "fly"
---

If you're deploying your app on Fly.io, you can add Subtrace in just a couple of steps.
Depending on the kind of [Fly builder](https://fly.io/docs/reference/builders) you're using,
the instructions are different.

We'll use a Python Uvicorn server as an example, but you can do this with any language and framework.

<Tabs>
  <Tab title="Dockerfile">
    Make the following changes to your app's Dockerfile:

    ```diff
    - CMD ["uvicorn", "main:app", "--host", "0.0.0.0"]
    + RUN curl -fsSLO "https://subtrace.dev/download/latest/$(uname -s)/$(uname -m)/subtrace" && chmod +x ./subtrace
    + CMD ["./subtrace", "run", "--", "uvicorn", "main:app", "--host", "0.0.0.0"]

    ```

    Get a `SUBTRACE_TOKEN` from the **Tokens** page on the [dashboard](https://subtrace.dev/dashboard)
    and set it as a Fly.io secret:

    ```
    fly secrets set SUBTRACE_TOKEN=subt_...
    ```

    Deploy your app as you normally would:

    ```
    fly deploy
    ```

    That's it! You can now visit your app and make some requests to see them automatically appear in the Subtrace
    dashboard.

  </Tab>
  <Tab title="Buildpacks">

    If you have a custom buildpack, add this line to its `bin/build` file to download Subtrace:

    ```bash
    curl -fSLO "https://subtrace.dev/download/$(uname -s)/$(uname -m)/subtrace" && chmod +x ./subtrace
    ```

    Change the command(s) in your `fly.toml` file to use Subtrace:

    ```diff
    # fly.toml

    [processes]
    -   web = "uvicorn main:app --host 0.0.0.0"
    +   web = "./subtrace run -- uvicorn main:app --host 0.0.0.0"
    ```

    Get a `SUBTRACE_TOKEN` from the **Tokens** page on the [dashboard](https://subtrace.dev/dashboard)
    and set it as a Fly.io secret:

    ```
    fly secrets set SUBTRACE_TOKEN=subt_...
    ```

    Deploy your app as you normally would:

    ```
    fly deploy
    ```

    That's it! You can visit your app and make some requests to see them automatically appear in the Subtrace
    dashboard.

  </Tab>
</Tabs>
